Letter sorting machines



Dec. 20, 1960 F. c. D. STREETER LETTER SORTING MACHINES 2 Sheets-Sheet 1 Filed April 24. 1959 1 T .llri

//v yew-rag #14 64 4 waa ,4 7" TOR/V673 Dec. 20, 1960 F. c. D. STREETER LETTER SORTING MACHINES 2 Sheets-Sheet 2 Filed April 24, 1959 United States Patent LETTER SORTING MACHINES Frederick Charles David Streeter, Bristol, England, as-

signor to The Thrissell Engineering Company Limited, Easton Road, Bristol, England, a British company Filed Apr. 24, 1959, Ser. No. 808,697

Claims priority, application Great Britain Apr. 29, 1958 Claims. (Cl. 271-80) This invention concerns improvements in letter sorting machines.

In these machines a large number of compartments into which letters are to be sorted are arranged in a number of superimposed rows. A conveyor system is associated with each row whereby the letters are carried along over the tops of the compartments of such row and discharged into various compartments as determined by control devices which cause the letters to be discharged from the conveyor system into the proper compartment. The conveyor system consists of a large number of rollers between which a letter passes to be fed by the friction of the rollers. The present invention is concerned with improvements to a letter sorting machine of the kind having these conveyor systems.

In existing machines of the kind referred to it sometimes happens that a letter being conveyed along one of the compartment conveyors is caught by an obstruction, for the letters are naturally of different random sizes, and the machine has to be stopped to clear the jammed letter. As the lower rollers of each conveyor system run on fixed axes while the upper rollers of the co-operating set are pressed towards the rollers of the lower set by coil springs the only way of removing a letter is by pulling it, usually with the aid of tweezers. This is a slow and awkward method and often a letter gets damaged, and the present invention provides a conveyor system intended to overcome these difficulties.

According to the invention there is provided in a letter sorting machine having a conveyor for carrying letters along above a row of compartments, which conveyor comprises a series of driven rollers and a series of cooperating freely rotatable pressure rollers which are resiliently pressed into engagement with the letters, means for releasing the pressure of the series of pressure rollers when it is desired to remove a letter from the system.

The pressure rollers may be journalled on fixed spindles which are fixed to a taut but flexible strip-like memher, and springs, as leaf springs, may be constrained to press on the strip-like member when the latter is taut, to press the rollers into the operative position. Means may be provided to release the tension on the strip-like member to cause the leaf springs to relax and such means may comprise a lever pivotally attached to one end of the strip, said lever being pivoted in the machine frame with arrangements for locking it in position to tension the strip.

One way of carrying the invention into effect is shown on the accompanying drawings in which:

Figure l is a front elevation, partly in section, of part of a conveyor system;

Figure 2 is an end view of Figure 1 in the direction of arrow A; and partly in section,

Figure 3 is a view of Figure 1 illustrating the action of the device.

Referring to the drawings, driven rollers 1 are fixed to spindles 2, journalled in frames 3 and driven by a chain 2,965,374 Patented Dec. 20, 1960 (not shown) which engages sprockets such as 25, Figure 2. These rollers form the lower part of the conveyor system and letters carried along the system are discharged into various compartments 4 of a row. Above the rollers 1 are co-operating pressure rollers 5 which engage the upper faces of the letters and rotate by friction therewith so that letters are carried along the conveyor system. Near the entry end of the system one pressure roller marked 5a Figure l is journalled in a bracket 6, this roller being independently sprung by helical springs 7. The bracket is adjustably fixed to a further bracket 8 which is attached to a flexible strip 9 to which spindles 10 for the rollers 5 are fixed.

The left-hand end of the bracket 6 is pivoted at 11 to an arm 12 of a lever pivoted at 13. The other arm 14 of the lever is engaged by an eccentric 15 having a handle 16. In the position shown in Figure l the eccentric is pressing on the arm 14 and therefore the strip 9 is taut but if the handle 16 is moved in the direction of the arrow the tension is released. Another pressure roller 5b is separately sprung by a leaf spring 17 fixed to the bracket 6.

The pressure rollers 5 are pressed into the operative position by springs, shown in Figure l as curved leaf springs 18, which are attached at one end to the strip 9 and at the other end to rigid channel members 19. These springs 18 are however only curved when the strip is taut. When the eccentric 15 is rotated to slacken the strip-like member 9 the springs 18 straighten out and raise the rollers 5 and the strip from the position shown in Figure l. The action is clear from Figure 3.

In order to be able to adjust the tautness of the flexible strip 9 the roller 5a is connected to the next roller in succession by an adjustable pin 20. In order to give the connection a certain amount of universal flexibility the end of the pin engages a self-aligning ball race 21 in the bracket 8.

Some other details are shown on the drawing and although these are not relevant to the actual invention they help in the understanding of the general conveyor system. The spindle 2 is bored throughout its length and inside it is journalled a rod 22. At the front of the conveyor the rod has a lever 23 on it and at the other end there is another lever (not shown) which is tripped when necessary so that the appropriate letter is delivered to a particular compartment. As will be seen from Figure 1, above each compartment is a guide 24 and these guides are attached to the levers 23 so that when a lever is rocked the attached guide is partially rotated and a letter delivered to the neighbouring compartment or passed along towards succeeding compartments if the lever is not rocked, as the case may be. The springs 18 are attached to the channel members as previously remarked and these members also serve as supports and locating guides for the row of compartments belonging to the next conveyor, the compartments having cooperating channels attached to their lower surfaces.

What I claim as my invention and desire to secure by Letters Patent is:

1. In a letter sorting machine, a conveyor for carrying letters above a row of compartments, said conveyor comprising a series of driven rollers and a series of coacting idler rollers resiliently pressed into engagement with the letters, a fixed member, a plurality of springs, each spring acting between said fixed member and one of said pressure rollers, and means operable (1) to flex said springs concurrently to press said pressure rollers resiliently into engagement with said letters, and (2) to relax said springs to relieve concurrently the pressure exerted by said pressure rollers on the letters to permit withdrawal of a letter from the conveyor.

2. In .a -letter sorting machine, a conveyor for carrying letters above a row ,of compartments, said conveyor comprising a series of driven rollers and a series of coacting idler rollers resiliently pressed into engagement with the letters, a plurality ofleaf springs each spring having one end fixed and its other end connected to one .pressure rollerson .said member, and devices for applying and releasing lengthwise tension on said member to -fiex and release said springs.

3, In a letter sorting machine, a conveyor for carrying letters above a row of compartments, said conveyor comprising a series of driven rollers and a series of coacting idler rollers resiliently pressed into engagement with the letters, a plurality of leaf springs each spring having one end fixed and the free end connected to one of said pressure rollersfa nd an elongated flexible member connecting the free ends of said springs and operable when under longitudinal tension to flex said springs concurrently to press said pressure rollers resiliently into engagement with the letters;

4. A conveyor as claimed in claim 3 including means to release the tension on said flexible member to cause thespringsto relax.

' 5. A conveyor as .claimed in claim 4, wherein said means comprises a lever pivotally attached to one end of the strip-like member theother end being fixed, said lever being pivoted ona fixed pivot, and devices for lockingsaidlever in 'a positionito tension ,the' strip.

References Cited in the file of this patent UNITED STATES PATENTS 

